It is often necessary to use conveyors to transport material to or from a "clean room" or from one place to another therewithin. A "clean room" is a room that is kept substantially contaminant-free by employing air filters, lint-free clothing for workers and the like. Such rooms are particularly suitable for the handling of precision parts, medical devices and the like. Conveyor devices such as belts and rollers can carry substantial amounts of particulate contaminants from exterior areas into a clean room. Moreover, in operation, the conveyor apparatus itself can generate dust, particles of material, and other contaminants simply through the interaction of its moving parts.